BALTIMORE — Rubby De La Rosa, who joined the Red Sox on Friday, and Alfredo Aceves are the two pitchers the Red Sox are considering for a spot start on Tuesday at Fenway Park in one game of a doubleheader.

What about Triple-A Pawtucket right-hander Allen Webster, who's made two spot starts this season, or Anthony Ranaudo, the Double-A Portland right-hander who's been dominant? Neither are at the top of the totem pole at the moment, for separate reasons.

Sox manager John Farrell said Friday the likely plan for Webster is to keep him at Pawtucket for now.

"Still trying to get more consistent strike throwing from him," Farrell said. "And whether that's best served through staying the course through the development path, we're in a situation where we need performance. That's not to say he's not capable, but there might be guys a little more ready in the short term."

Webster has great stuff, and on Friday tossed six innings of one-hit, shutout ball. That outing, however, wasn't finished when Farrell spoke to reporters, and Webster lasted just 3 1/3 innings and allowed five runs in his prior start, June 6. In a four-start stretch from May 19-June 1, Webster walked a combined 14 in 22 innings.

Webster's two major league outings this season were disaparate: two runs in six innings in April, compared to eight runs in 1 2/3 innings in May.

"I wouldn’t say there's a difficulty throwing strikes," Farrell said. "He's just not shown the consistency that he showed in spring training and the first start (in the majors) you mentioned. And we know here, the game can speed up guys. The strike zone can be a little bit more consistent, a little bit more strict. All things considered, that's why we're looking at Ace or Rubby in that situation."

Ranaudo, meanwhile, is 7-1 with a 2.15 ERA for Portland. He's struck out 76 in 67 innings while walking 21 and allowing just three home runs. He set a career-high with 13 strikeouts in his most recent outing on Thursday, tying Portland's club record.

Jon Lester was the last Sea Dogs pitcher to rack up 13 strikeouts, in 2005.

"There are no whispers about [a callup]. The organization doesn't tell you to do this or that and you'll be called up. I just want to keep taking the ball every fifth day and try to help my team the best I can," Ranaudo said according to MiLB.com. "This is a pretty fun team here in Portland."

Ranaudo has re-established himself as a top prospect after injuries held him back last season. The Sox, too, have a 40-man roster spot following Pedro Ciriaco's removal, but they're not looking to rush anything.

"There's guys ahead of him," Farrell said. "And even though we have a spot on the roster right now, I don't know that we want to force-feed that as well. One thing is, he's obviously making very good progress this season. Last night's performance was a dominant one for him. The one thing you want to be careful of is, while he's got momentum going, you want to be careful that you don’t force-feed it and maybe jump it a little bit too quick. Most importantly, he's having a very good year."